# Speeding up the exit(); restart REPL loop in VSCode

**URL:** <https://discourse.julialang.org/t/speeding-up-the-exit-restart-repl-loop-in-vscode/56834>\
**Category:** VS Code\
**Created:** [March 9, 2021, 10:02pm UTC](https://discourse.julialang.org/t/speeding-up-the-exit-restart-repl-loop-in-vscode/56834 "2021-03-09T22:02:08Z")\
**Posts on this page:** 9\
**Page:** 1

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**Author:** ![marty0801](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/marty0801/32/12715_2.png) [@marty0801](https://discourse.julialang.org/u/marty0801)\
**Post date:** [March 9, 2021, 10:02pm UTC](https://discourse.julialang.org/t/speeding-up-the-exit-restart-repl-loop-in-vscode/56834/1 "2021-03-09T22:02:08Z")

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I use Revise, but I frequently change struct definitions, which requires to exit Julia and start another REPL, wait for my package to compile. You know the drill; there must be a better way! How do you handle this?

The perfect solution would be for VSCode to always have two REPLs open, automatically opening a new one and loading my code whenever I close a stale REPL.

…any chance someone knows how to do this?

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**Author:** ![heliosdrm](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/heliosdrm/32/3851_2.png) [@heliosdrm](https://discourse.julialang.org/u/heliosdrm)\
**Post date:** [March 9, 2021, 11:31pm UTC](https://discourse.julialang.org/t/speeding-up-the-exit-restart-repl-loop-in-vscode/56834/2 "2021-03-09T23:31:40Z")

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I think that having two simultaneous REPLs in VSCode is not yet supported, but there is ongoing work related to that; see:  
[https://github.com/julia-vscode/julia-vscode/issues/1030](https://github.com/julia-vscode/julia-vscode/issues/1030)

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**Author:** ![marty0801](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/marty0801/32/12715_2.png) [@marty0801](https://discourse.julialang.org/u/marty0801)\
**Post date:** [March 10, 2021, 1:33am UTC](https://discourse.julialang.org/t/speeding-up-the-exit-restart-repl-loop-in-vscode/56834/3 "2021-03-10T01:33:57Z")

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I wonder why it’s unsupported. It’s trivial to open several python interpreters; why not so for Julia?

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**Author:** ![davidanthoff](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/davidanthoff/32/223493_2.png) [@davidanthoff](https://discourse.julialang.org/u/davidanthoff)\
**Post date:** [March 10, 2021, 2:48am UTC](https://discourse.julialang.org/t/speeding-up-the-exit-restart-repl-loop-in-vscode/56834/4 "2021-03-10T02:48:04Z")

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We provide very tight integration between the REPL and the UI in VS code with things like the workspace explorer etc, and those UI elements currently all assume that there is only one Julia REPL. We do plan to support more than one, but it will require a fair bit of work in the extension to robustly support that scenario.

You can of course always run multiple instances of Julia in shell instances that you start inside VS Code, but those won’t be hooked up to the integration points that the Julia extension provides (code execution, plot gallery etc.)

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**Author:** ![pfitzseb](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/pfitzseb/32/45566_2.png) [@pfitzseb](https://discourse.julialang.org/u/pfitzseb)\
**Post date:** [March 10, 2021, 8:35am UTC](https://discourse.julialang.org/t/speeding-up-the-exit-restart-repl-loop-in-vscode/56834/5 "2021-03-10T08:35:22Z")

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I’d suggest using inline evaluation to re-define your whole module, which allows for structs to be changed all you want (with the caveat that you need to redefine all previous instances of your structs to work with the “new” module’s functions). That usually gets you around needing to restart.

The idea of keeping multiple Julia process around to connect to is something we had in Juno, but usually caused more issues than it was worth. Without trying to restore at least the loaded packages it’s also not a tremendous time saver.

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**Author:** ![marty0801](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/marty0801/32/12715_2.png) [@marty0801](https://discourse.julialang.org/u/marty0801)\
**Post date:** [March 10, 2021, 9:54pm UTC](https://discourse.julialang.org/t/speeding-up-the-exit-restart-repl-loop-in-vscode/56834/6 "2021-03-10T21:54:39Z")

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I can’t get this to work; could you elaborate? I have

```julia
module ToyMod 
export Toy 

struct Toy
   a::Int 
end 

end

```

which I send to the REPL. I can successfully execute

```julia
using .ToyMod
toy=Toy(3)

```

Now I change `ToyMod.Toy` to include the additional `b::Int`; re-execute ToyMod in the REPL, but when I `toy=Toy(3,4)`, it throws a MethodError.

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<div class="post-metadata">

**Author:** ![heliosdrm](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/heliosdrm/32/3851_2.png) [@heliosdrm](https://discourse.julialang.org/u/heliosdrm)\
**Post date:** [March 10, 2021, 11:31pm UTC](https://discourse.julialang.org/t/speeding-up-the-exit-restart-repl-loop-in-vscode/56834/7 "2021-03-10T23:31:03Z")

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Maybe you also repeated `using .ToyMod` after redefining `ToyMod`? If you did, then you should have seen something like:

```julia
WARNING: using ToyMod.Toy in module Main conflicts with an existing identifier.

```

This would mean that there is already a definition of the struct `Toy` in `Main` (the one imported the first time you executed `using .ToyMod`), and you are trying to modify it, which is not allowed. If you redefine the whole module, but don’t export `Toy` (or don’t try to import it twice), there should be no conflict, and `ToyMod.Toy` should reflect the new definition. (But if you already have some `Toy` object created with the older definition, then the situation can be messy.)

(This doesn’t work if you are tracking the module definition with Revise. You must really rebind `ToyMod` to a new module object, not just try to modify the definitions inside it, as said before regarding `Maain`.)

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**Author:** ![marty0801](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/marty0801/32/12715_2.png) [@marty0801](https://discourse.julialang.org/u/marty0801)\
**Post date:** [March 11, 2021, 10:32am UTC](https://discourse.julialang.org/t/speeding-up-the-exit-restart-repl-loop-in-vscode/56834/8 "2021-03-11T10:32:30Z")

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Got it. Thanks; it works now. To clarify, your suggestion still works if Revise is enabled. (Your parenthetical suggests otherwise). In short:

1. Execute the module definition in the REPL
2. Within the REPL do

```julia
julia> using .ToyMod 
julia> toy= ToyMod.Toy(3) 

```

1. Now change ToyMod
2. Re-execute it back in the REPL.

`ToyMod.Toy` will reflect the new module definition.

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<div class="post-metadata">

**Author:** ![heliosdrm](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/heliosdrm/32/3851_2.png) [@heliosdrm](https://discourse.julialang.org/u/heliosdrm)\
**Post date:** [March 11, 2021, 6:43pm UTC](https://discourse.julialang.org/t/speeding-up-the-exit-restart-repl-loop-in-vscode/56834/9 "2021-03-11T18:43:32Z")

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> [@marty0801](#):
>
> To clarify, your suggestion still works if Revise is enabled. (Your parenthetical suggests otherwise).

Right, having Revise enabled won’t affect. What I meant is that the problem happens if you _track_ the module with Revise. For instance, if you have the code of `ToyMod` in a file and load it with `includet` (not `include`).